<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box{
            position: relative;
            width: 300px;
            height: 300px;
            margin: 100px auto;
            transform-style: preserve-3d;
            transition: all 1s;
        }
        .box:hover{
            transform: rotateY(180deg);
        }
        .front,
        .back{
            position: absolute;
            top:0;
            left: 0;
            width: 100%;
            height: 100%;
            border-radius: 50%;
            text-align: center;
            line-height: 300px;
            font-weight: bold;
            color: white;
            font-size: 30px;
        }
        .front{
            background-color: blue;
        }
        .back{
            background-color: pink;
            transform: rotateY(180deg);
        }

    </style>
</head>
<body>
<div class="box">
    <div class="front">加油</div>
    <div class="back">前端工程师</div>
</div>
</body>
</html>